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I am making a board which will communicate wirelessly with a smart phone. When I send a specific command, I want it to sound an alarm to the user, making it able to be found when lost. I've got everything working with the device and I got the piezo buzzer to sound.

Problem is the piezo is quiet with it's 3v nominal voltage.. Any solutions towards a louder device that's small enough for one to wear on their keychain?

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  • \$\begingroup\$ How loud do you want it? \$\endgroup\$ – Andy aka Mar 26 '15 at 22:36
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    \$\begingroup\$ Piezo sounders have a resonant frequency. If you oscillate it at that frequency you will get much more volume. \$\endgroup\$ – Majenko Mar 26 '15 at 22:42
  • \$\begingroup\$ Piezo noisemakers are a flat diaphragm mounted over top of a resonant cavity. The peizo element has a natural resonant frequency and the cavity is tuned to that same frequency. You may not be operating your piezo sounder at its' correct frequency. Or: you may need a better sounder. It's sorta hard for us to tell right now. \$\endgroup\$ – Dwayne Reid Mar 26 '15 at 22:50
  • \$\begingroup\$ A side note, I would also recommend pulsing the sound. At the higher frequencies piezo transducers are likely to output, people will have a hard time localizing it. \$\endgroup\$ – Jarrod Christman Jun 1 '15 at 20:17
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When a piezo buzzer is not delivering enough volume, the most like root cause is one of the following:

  • Input signal is too weak A signal may need an amplification stage before the piezo (even a venerable LM386 or similar would do)
  • Response is poor for input signal frequency piezo buzzers typically work best over quite a limited band, say 2-5kHz with a peak around 4kHz.
  • The particular piezo component is not up to the job 3V may be at the lower end of what they need to drive a decent sound. Use a test signal to verify it can actually generate the volume you are after. It might just be a dud unit, or maybe another brand/model would work better. Check the datasheet if possible (although I know for piezo buzzers they can be hard to find and verify they apply to the unit in your hand!).

NB: This Peizoelectric Audio Components Application Manual by Murata is one of a few that include a some good details of how to drive peizos and considerations that apply.

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